The proposed study investigates the cognitive, linguistic and academic effects of unilateral infarctions in children following cardiac catheterization. Two groups of children will be studied: Group I will include all children who incurred unilateral infarctions following catheterization at the Catheterization Laboratory at Rainbow Babies and Childrens Hospital from 1975 to the present; Group II will include children who incur unilateral infarctions following catheterizaiton at Rainbow Babies and Childrens Hospital from 1981-83, but who will have been seen for cognitive, linguistic and neurological assessment prior to catheterization. Control children will be included for each group. Only children evidencing no known neurological or genetic abnormalities prior to catheterization will be included in the longitudinal study. All subjects will be followed at a fixed post-catheterization schedule to chart any cognitive, linguistic or academic deficits and changes that occur during development. Measures will include: verbal and nonverbal intelligence; comprehension and production of specified phonological, syntactic and semantic aspects of language; and reading, arithmetic and spelling achievement. Comparisions will be made between the performance of the subjects with unilateral infarctions and their matched controls, between right and left hemisphere lesioned children, between those with anterior versus posterior lesions and between children whose infarctions occurred prior to versus after the onset of speech at one year of age. This neurolinguistic study addresses the hypothesis of hemisphere equipotentiality for language in children and aims to provide objective data documenting the cognitive, linguistic and academic ability of this well-defined group of children with unilateral infarctions.